This invention relates generally to a mounting device for use in a non-invasive tonometry system. Mere particularly, this invention relates to a wrist mount device for use in non-invasively monitoring a patient's blood pressure while providing stability to the placement of the tonometry sensor relative to the patient's anatomy.
Routine methods of monitoring a patient's blood pressure include the widely used auscultatory method known as the Korotkoff method. This method is non-invasive, however, it only provides a measurement of systolic and diastolic pressure on an intermittent basis; it does not provide the entire waveform on a continuous basis. Furthermore, the use of the Korotkoff method often yields inaccurate results. Moreover, the rate at which blood pressure can be recorded is limited by the inflation and deflation rate of the occlusive cuff. Therefore, true beat-to-beat continuous blood pressure monitoring is not possible using this method.
Other methods include the use of intra-arterial catheters that are invasively inserted within a patient's artery. Although such invasive methods often yield accurate results, the potential trauma to a patient often outweighs the benefits of using such a method. Further, invasive tonometry methods are cumbersome in that sterilization of the various apparatus used in conjunction with the invasive catheter is often difficult to maintain. Further, a significant risk in using an invasive method of monitoring blood pressure includes the possibility of introducing air bubbles into the patient's blood stream.
Recent developments in tonometry include the development of non-invasive tonometry sensors that monitor the blood pressure waveform as a function of tissue stress in the tissue overlying an artery of interest. One example of such a sensor is disclosed in U.S. Pat. No. 5,158,091. With the advent of such non-invasive sensors, continuous, accurate blood pressure measurements have become possible. In order to achieve accurate blood pressure measurement utilizing such a non-invasive tissue stress sensor, however, it becomes necessary to ensure that the sensor is maintained in proper communication with the tissue overlying the artery of interest. For example, it is necessary that the tissue stress sensor be maintained in controlled contact with the overlying tissue such that unnecessary relative movements between the tissue and the sensor do not introduce undesirable error or artifacts into the blood pressure measurement.
It is therefore necessary and desirable to provide a device that maintains a tissue stress sensor in proper communication with the overlying tissue in a predictable fashion. Moreover, it is important that a patient be restricted from unnecessary movement of that portion of the anatomy where the tissue stress sensor is located in order to avoid a misplacement of the sensor relative to the artery of interest. It is also important to provide a mounting device for the tissue stress sensor that takes into consideration patient comfort and economics of use. Further, it is desirable to provide a device for mounting a tissue stress sensor on a selected portion of a patient's anatomy that is readily usable on a variety of patients.